If Arlen Specter believed he was doing an end-run on challenges from within his old political party, he may have to rethink things.

A new poll out yesterday from Quinnipiac University shows the longtime Pennsylvania senator, who stunned the political world last week with his announcement that he was abandoning the Republican Party and crossing the aisle to become a Democrat, likely made the right call. But that does not mean his problems are over.

Specter made the move because his own polling data told him he was going to lose in the Republican Primary to conservative former Congressman Pat Toomey. Ever the pragmatist, Specter skirted that problem by switching parties. He may face a challenge from either Joe Torsella, the head of the Constitution Center, or our own Joe Sestak, the 7th District Congressman who is not yet ready to join the party leadership in backing Specter. We heard Sestak was meeting with some local labor leaders to gauge their support.

But that might not even be Specter’s biggest problem. While the poll shows Specter as a Democrat with a healthy lead over Toomey in a general election vote, that assumes that Toomey will be the Republican candidate.

There is a persistent drumbeat that Republicans, leery about whether Toomey can attract enough support in a statewide race, may turn to former governor and homeland security boss Tom Ridge.

The poll shows Specter and Ridge in almost a dead heat.

For his part, Ridge is not talking about a possible run. But if the numbers hold showing Specter vanquishing Toomey, look for Republicans to cast their eyes to the former governor.

It could be Heartbreak Ridge for Darlin’ Arlen.